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Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most warm-blooded animals. The primary host is the felid (cat) family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself recently been infected, and by transmission from mother to fetus. Cats are the primary source of infection to human hosts, although contact with raw meat, especially lamb, is a more significant source of human infections in some countries. Fecal contamination of hands is a significant risk factor.

Up to a third of the world's human population is estimated to carry a Toxoplasma infection. The Centers for Disease Control and Prevention notes the overall seroprevalence in the United States as determined with specimens collected by the National Health and Nutritional Examination Survey (NHANES) between 1999 and 2004 was found to be 10.8%, with seroprevalence among women of childbearing age (15 to 44 years) 11%. 

Toxoplasmosis is considered to be a leading cause of death attributed to foodborne illness in the United States. More than 60 million men, women, and children in the U.S. carry the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness.

During the first few weeks after exposure, the infection typically causes a mild, flu-like illness or no illness. However, those with weakened immune systems, such as those with AIDS and pregnant women, may become seriously ill, and it can occasionally be fatal. Toxoplasmosis is considered one of the Neglected Parasitic Infections, a group of five parasitic diseases that have been targeted by CDC for public health action.

Source: Centers for Disease Control and Prevention